ML031900241
| ML031900241 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 06/26/2003 |
| From: | Shriver B Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-96-006, PLA-5613 | |
| Download: ML031900241 (7) | |
Text
Bryce L Shriver Senior Vice President and Chief Nuclear Officer PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3120 Fax 570.542.1504 blshriver pplweb.com JUN 26 2003 pp I
4
,TM U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Mail Stop OP1-17 Washington, DC 20555 SUQUEHANNA STEAM ELECTRIC STATION SUPPLEMENTAL RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-06 DATED JULY 26, 2001 PLA-5613 Docket Nos. 50-387 and 50-388
References:
1)
PLA-5093, R. G. Byram (PPL) to USNRC, "Generic Letter 96-06 Risk Assessment, "
dated August 3, 1999.
- 2)
USNRC to R. G. Byram (PPL), "Requestfor Additional Information Regarding Supplemental Response to Generic Letter 96-06 (TAC Nos. M96875 and M96876),"
dated July 26, 2001.
- 3)
PLA -5352, R. G. Byram (PPL) to USNRC, "Response to Requestfor Additional Information Regarding Supplemental Response to Generic Letter 96-06 dated July 26, 2001, " dated September 5, 2001.
- 4)
PLA-5400, R. G. Byram (PPL) to USNRC, "Response to Requestfor Additional Information Regarding Supplemental Response to Generic Letter 96-06 dated July 26, 2001, " dated December 3, 2001.
On July 26, 2001, the NRC staff transmitted a request for additional information regarding the PPL Susquehanna, LLC (PPL) risk assessment generated in response to Generic Letter 96-06, "Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions." PPL's response was provided in References 3 and 4.
Reference 4 provided an evaluation of the eleven containment piping penetrations (per unit) identified as being susceptible to thermally induced overpressurization. Two penetrations were quantitatively analyzed and nine were qualitatively analyzed.
In a teleconference held on February 10, 2003, NRC requested that PPL perform a quantitative analysis on the nine penetrations that PPL had qualitatively analyzed.
4UD7; Document Control Desk PLA-5613 The requested quantitative analysis has been completed. The attachment to this letter documents the results of the analysis. The analysis shows that overpressurization will not result in pressure boundary failure of the piping or valves in these penetrations. The results are provided in the form of an updated response to Question 8 of Reference 2. The revised portions are identified by revision bar in the right hand margin.
If you have any questions, please contact Mr. Michael H. Crowthers at (610) 774-7766.
Sincerely, B. L. Shriver - Revised Response to NRC Question 8 copy: NRC Region I Mr. R. V. Guzman, NRC Project Manager Mr. S. Hansell, NRC Sr. Resident Inspector Mr. R. Janati, DEP/BRP to PLA-5613 Revised Response to NRC Question 8 to PLA-5613 Page 1 of 4 NRC Question 8:
Provide the results of piping and valve analysis based on the criteria contained in the American Society of Mechanical Engineers Code,Section III, Appendix F. For each component, provide a summary of the maximum faulted pressure, design load combination, calculated stress for design load combination including faulted pressure, and allowable stress based on the criteria contained in Appendix F. Also, you should include a reference to the specific provisions of Appendix F used as a basis in calculating the allowable stress (e.g., F-1331, F-1430, F-1420).
PPL Response:
The eleven containment piping penetrations (per unit) identified as being susceptible to thermally induced overpressurization have been evaluated for their pressure retention capability. The process piping located between the containment isolation valves associated with each penetration was evaluated using the criteria provided in the ASME Boiler & Pressure Vessel Code,Section III, Appendix F. Paragraph F-1430 has been used as a basis for calculating the allowable stresses. The results of the evaluation are provided here.
F-1430(a) states that the internal pressure shall not exceed 200% of the Design Pressure calculated in accordance with Eq.(2) of NB-3641.1. An allowable pressure for each piping penetration was determined using Eq.(2). The pressure limit is based on nominal wall thickness with a corrosion allowance. Table 1 below provides the allowable pressure for each penetration along with maximum post-LOCA temperatures and pressures.
The results demonstrate that the predicted maximum pressures for all of the lines are within the allowable pressure limits.
F-1430(b) states that Eq.(9) of NB-3652 shall be satisfied using a stress limit of the lesser of 3.OSm or 2Sy. The hoop stress portion of Eq. (9) was determined using the maximum post-LOCA pressure associated with each line. The maximum Faulted stress for each line was extracted from the existing piping calculations and used for the mechanical stress portion of Eq.(9). These existing stresses are based on design basis Faulted load combinations that include pressure, deadweight, seismic and hydrodynamic loadings.
Table 2 provides a tabulation of the Eq.(9) stresses and the allowables used.
The results demonstrate that all of the piping stresses are within allowable Appendix F limits.
to PLA-5613 Page 2 of 4 Initially, a qualitative assessment of each penetration was performed in order to assess the susceptibility of the subject valves to an overpressurization failure. Based on a review of the isolation valves associated with the eleven penetrations, nine contain inboard and outboard isolation valves of a different type and design. It was initially concluded that because of the distinct design characteristics of these valves, the likelihood of simultaneous failure of the inboard and outboard isolation valves is negligible. Based on an NRC verbal request, a quantitative analysis, similar to that performed for the valves associated with Containment Penetrations X-23 and X-241, was performed for the valves associated with each of the affected Containment Penetrations. Table 3 provides a summary of the results of this evaluation.
As can be seen from the results in Table 3, for all penetrations, pressure relief will occur through leakage at a pressure value lower than the pressure retaining capability of the associated piping. As a result, the calculated maximum pressure, Pm, listed in Table 1 will not be reached and the pressure boundary for the valves and piping in these penetrations will not be ruptured. Therefore, for all of the penetrations, pressure relief will occur via a leakage path rather than through a catastrophic pressure boundary failure.
The remaining two penetrations (X-23 and X-24) contain isolation valves that are of the same design (flex-wedge gate valves). A quantitative analysis has been performed by the valve vendor in order to determine if the subject valves are capable of accommodating the predicted post-LOCA pressures. This analysis employed allowable stress criterion based on ASME Section III, Appendix I. The analysis concludes that the body-bonnet flange would leak prior to reaching 12322 psi. This leakage would serve to release any build-up of pressure and thus would preclude overpressurization failure. It is therefore, concluded that gross failure of the valves is not expected.
In addition, the limiting pressure associated with the structural capability of the subject valves is 3566 psi which bounds the maximum post-LOCA pressure of 2280 psi (X-23 penetration) and 2420 psi (X-24 penetration).
l The allowable stresses were based on ASME Section III Appendix I using either the Service Level D allowable stress level or the material yield stress.
2 The value of 900 psi previously reported in PLA-5400 dated December 3, 2001 was based on bolt tension due to internal pressure exceeding 1.5 times the allowable bolt stress. This reported value is based on bolt tension due to internal pressure exceeding the bolt pre-load stress resulting from the bolt tightening operation.
to PLA-5613 Page 3 of 4 Table 1. Pressure Limits In Accordance With F-1430(a) lPenetraffon DpJ{,
j WUlol (Psi)
Comments X-85A 3"
3010 118 5143 Pmax < Pallowable X-85B 3"
2810 120 5143 Pmax < Pallowable X-86A 3"
4570 139 5143 Pmax < Pallowable X-86B 3"
4400 142 5143 Pmax < Pallowable X-23 4"
2280 133 4360 Pmax < Pallowable X-24 4"
2420 135 4360 P.ax < Pallowable X-17 6"
4600 160 5473 Pmax < Pallowable X-54 8"9 2570 114 3059 P~p.~ < Pallowable X-53 8"
2970 117 3059 Pmiax < Pallowable X-56 8"
2570 114 3059 Pax < Pallowable X-55 8"9 3030 114 3059 Pmiax < Pa.owable Table 2. Stress Limits In Accordance With F-1430(b)
Pentrationpll pl Hoop iMech Stress Total Stress 3.0 Sm or 2.0 Sy Pene(Stress (psi) psi)
(psi)
(psi)
X-85A 3"
12193 16399 28592 60000 X-85B 3"
11383 16038 27421 60000 X-86A 3".
18513 10324 28837 60000 X-86B 3"
17824 9122 26946 60000 X-23 4"
10823 20451 31274 60000 X-24 4"
11487 10166 21653 60000 X-17 6"
17636 21853 39489 50200 X-54 8"
17210 13668 30878 60000 X-53 8"
19888 13576 33464 60000 X-56 8"
17210 10255 27465 60000 X-55 20290 10118 30408 60000
Attachment I to PLA-5613 Page 4 of 4 iTable 3 Component Level Weak-Link Matrix for I
Containment Penetration Valves Outboard Valve - Critical Pressures Inboard Valve -CriticalPressures(psi)
(psi)~~~~~~~~~(pi Pene. No.
I Valve Disc Piping Flange Valve Disc Bonnet IBonnet Body Leakage Leakage Body Leakage leakage X-85A 4233 2078 18753 6748 2812 5069 X-85B 4233 2078 18753 6748 2812 5069 X-86A 4233 2078 1875 6748 2812 5069 X-86B 4233 2078 1875 6748 2812 5069 X-17 8349 7432 3502 8548 3794 4744 X-54 4334 381 1450 3391 571 33437 1450 3391 1338 1147 X-53 4334 381 1450 4291 571 3353 X-56 4334 381 1450 4288 571 3353 X-55 4334 381 1450 4288 571 3353 3 The value of 1,850 psi reported in PLA-5352 dated September 5, 2001 in response to NRC Question No. 3 was based on a spiral-wound stainless steel asbestos filled gasket. The value of 1,875 psi presented here is based on a spiral-wound stainless steel flexible-graphite filled gasket.